This invention relates generally to efficient antenna designs for mobile communications devices, and systems to reduce the electromagnetic radiation emitted by wearable mobile devices.
Mobile electronic devices are increasingly popular, and demand for wearable wireless devices, including personal location devices, trackers, and mobile personal emergency response systems is expected to grow in the coming years. Smartphones and typical handheld mobile devices do not meet all of the current demand for wireless tracking and similar applications.
For these devices to achieve maximum acceptance, they must be small enough and efficient enough to be packaged in a small form factor with excellent battery life and wireless communications capabilities. For example, these devices, for many applications, must use long-range wireless communications to communicate with wireless base stations, often using the cellular networks at frequencies such as 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. Such devices may also use short-range wireless communications links, including Wi-Fi™ (IEEE 802.11) band at 2.4 GHz and the Bluetooth™ band at 2.4 GHz, as well as proprietary technologies like Zigbee, ZWave, and ANT+. Communications are also possible in data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System band).
To satisfy consumer demand for small form factor wireless communications devices, manufacturers are continually striving to reduce the size of components that are used in these devices. For example, manufacturers have made attempts to miniaturize the antennas used in handheld electronic devices.
A typical antenna may be fabricated by patterning a metal layer on a circuit board substrate or may be formed from a sheet of thin metal using a foil stamping process. Antennas such as planar inverted-F antennas (PIFAs) and antennas based on L-shaped resonating elements can be fabricated in this way. Antennas such as PIFA antennas and antennas with L-shaped resonating elements can be used in handheld devices.
In order to meet government-imposed requirements for wearable wireless devices, antennas must be both small and extremely efficient, requiring less power (and resulting electromagnetic radiation) to send wireless signals.
It would therefore be desirable to be able to provide improved antenna structures for wearable wireless electronic devices, as well as systems designed to reduce the emissions of electromagnetic radiation from said devices.